Re: [PATCH v4 03/21] ARM64: implement pci_remap_cfgspace() interface
- Date: Thu, 20 Apr 2017 11:33:40 +0100
- From: Catalin Marinas <catalin.marinas@xxxxxxx>
- Subject: Re: [PATCH v4 03/21] ARM64: implement pci_remap_cfgspace() interface
On Wed, Apr 19, 2017 at 05:48:52PM +0100, Lorenzo Pieralisi wrote:
> The PCI bus specifications (rev 3.0, 3.2.5 "Transaction Ordering
> and Posting") defines rules for PCI configuration space transactions
> ordering and posting, that state that configuration writes
> are non-posted transactions.
> This rule is reinforced by the ARM v8 architecture reference manual
> (issue A.k, Early Write Acknowledgment) that explicitly recommends
> that No Early Write Acknowledgment attribute should be used to map
> PCI configuration (write) transactions.
> Current ioremap interface on ARM64 implements mapping functions
> where the Early Write Acknowledgment hint is enabled, so they
> cannot be used to map PCI configuration space in a PCI specs
> compliant way.
> Implement an ARM64 specific pci_remap_cfgspace() interface
> that allows to map PCI config region with nGnRnE attributes, providing
> a remap function that complies with PCI specifications and the ARMv8
> architecture reference manual recommendations.
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
> Cc: Will Deacon <will.deacon@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>